Geolocation of a Known Altitude Target Using Azimuth Measurements Based on the Ellipsoidal Expansion in Normal Direction of WGS-84 Model

This paper addresses the problem of geolocation of a known altitude target using azimuth measurements. Traditionally, it is modeled by a quadratic constrained least squares (QCLS) problem, whereby the known altitude information is used to establish the equality constraint based on the spherical Earth model. However, the inaccurate Earth model would introduce a deterministic bias. We propose an ellipsoidal expansion scheme using the known altitude via the Wideband Geodetic System (WGS-84) model, which can help establish a more accurate constraint with respect to the target position. In our model, the target geolocation is also formulated as a QCLS problem, but with this proposed novel constraint. The Lagrange multiplier combining with the Newton’s iterative methods is used to solve this resulting constrained optimization problem. Simulations demonstrate the comparative advantages of the proposed method.